Building the Brains for a Budget Racer: Jaguar A7 #42

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m2cupcar
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Building the Brains for a Budget Racer: Jaguar A7 #42

Post by m2cupcar »

Jagaur A7 #42 is in the works. If all goes well, it will be the brains for a 2016 Grassroots Motorsports Challenge entry.
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Re: Building the Brains for a Budget Racer: Jaguar A7 #42

Post by Fred »

Awesome! :-)
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Re: Building the Brains for a Budget Racer: Jaguar A7 #42

Post by m2cupcar »

Progress! Lots of LEDs to go down, INJ jumpers and configuration for 95 Miata components.
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I am utilizing the factory wiring harness, connector and ecu case for a simplified installation. Strategy below. Letter/number/color is pinout reference to OE ECU connector/wiring.

IAT
- 2P red/blue

POWER
- 12v-SW - 1C violet - (hot while cranking - ECU power)
- BRV-12v - 1A blue/red - (HOT always)
(note: 1B is Main Relay 12v: FP, injectors, data connector @ fender, EGR solenoids vacuum/vent, purge, IAC, pressure regulator control solenoid valve @ front of engine)

RPM Hall/Opto
- configure: connect RPM0- and RPM1- to RPM0 RPM1 Shields
- R16, 17, 18, 19 = 1K 1/4w resistors
- R22, 83, 21, 84 = 1k 1/4w resistors
- R20, 23 = no resistors
- RPM0+ (crank) - 2E White CAS
- RPM1+ (cam) - 2G Yellow/Blue CAS

HSD (fuel pump)
- configure: jumper FP center pin HSD pin, connect 2T/fuel pump to HSD pad
- HSD - 2T lightgreen (fuel pump)

GROUNDS
- GND - 2A to engine block
- GND2 - 2B to engine block
- Sensor-GND - 2D (OE ground circuit for sensors: O2, MAF, CHT, EGR, TPS)
(note: 2C to engine block but connects after joint connector X-35, 1K black/lightgreen to trans & ground joint connector X-35, 2F black/red (changes to black/green) to MAF & ground joint connector X-35)

IGNITION (wasted)
- IG1 - 1G brown/yellow (cyl 1/4)
- IG2 - 1H brown (cal 3/4)
- JP1 - 5v

CHT
- 2G - blue/white

TPS
- TPS - 2M Red/blue (signal)
- TPS-5v - 2K lightgreen/white
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Fuel Injectors

Post by m2cupcar »

Still trying to figure out the injector setup on the A7 and connections to the Miata harness/injectors.

FUEL INJECTORS
- Install 0ohm jumpers at JP3 JP4 & JP5
- INJ1 - 2Y green/white
- INJ2 - 2Z green
- INJ3 - 2U yellow
- INJ4 - 2V yellow/blue
(This is based on how the A3 injector connections were at P26, 27, 28, 29

What do I do for INJ1-GND, INJ2-GND, INJ3-GND, INJ4-GND?
And Injectors-IN?
90 Miata | 302rwhp @ 6450rpm | 281rwftlbs @ 4800rpm | FE-dohc 2.0L turbo
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Re: Building the Brains for a Budget Racer: Jaguar A7 #42

Post by Fred »

Great progress! Love the way you write things up. Super clear/easy for me. I know you've done decent research on the car side, so take my advice with a single grain of salt, it's probably good, but feel free to override it :-)
m2cupcar wrote:POWER
- 12v-SW - 1C violet - (hot while cranking - ECU power)
- BRV-12v - 1A blue/red - (HOT always)
(note: 1B is Main Relay 12v: FP, injectors, data connector @ fender, EGR solenoids vacuum/vent, purge, IAC, pressure regulator control solenoid valve @ front of engine)

GROUNDS
- GND - 2A to engine block
- GND2 - 2B to engine block
- Sensor-GND - 2D (OE ground circuit for sensors: O2, MAF, CHT, EGR, TPS)
(note: 2C to engine block but connects after joint connector X-35, 1K black/lightgreen to trans & ground joint connector X-35, 2F black/red (changes to black/green) to MAF & ground joint connector X-35)
Hmmm, a few things here don't look quite right.

1) BRV (Battery Reference Voltage) will be ever so slight of a battery drain over time - not a huge deal, but something to consider
2) 12V-SW (main power, switched by something, because otherwise the ECU would be forever on) will not continue functioning once the key is released
3) There is another third 12V input for the ignition drivers, HSD, and LEDs that you need to hook up and haven't listed.

If the feed to the relay that supplies 1B is solid, and the connection from that relay to 1B is independent, this might be the best bet for all three Jaguar connections. 1C is likely intended as a wake up signal to the stock ECU (we don't sleep, yet) and the always on 1A would be to supply the regulators and so forth so the OEM ECU can sleep and/or power itself down when it's ready. Hopefully Hentai jumps in here with his experience on this matter.

4) Hentai may know which ground is for what, too. He had it one way, and had some bad noise, and changed it around and it was good thereafter. Jaguar grounding intent:
  • GND + GND2 are intended to supply the CPU, all internal circuits, and, indirectly, all sensors, with quality precision ground signal. On a standalone install, you'd run two wires just for this, but factory strategies differ a bit.
  • Sensor GNDs are the same connection as GND and GND2, interchangeable, sort of, but intended for supplying ground out to sensors such as TPS, IAT, CHT, MAF, CAS, etc.
  • LSD-GND is an *isolated* ground for the 4 LSD FETs in two packages near the HSD driver. Intent is to keep noisy ground returns from solenoids and relays and the like away from the CPU and sensors.
  • Injector GNDs are like LSD but to keep the injector ground current out of the main reference ground lines, and optionally, from each other, too.
5) O2 and EGR grounds have heater/solenoid current dumped through them? or just ground references for inputs from those things?

Fundamentally:
  • Your PCB needs a solid reference ground, quite possibly the combination of 2C 1K 2F could provide this? Not sure. 2A/2B look highly attractive, but I don't see high current return paths available for the injectors and other junk if you use those for your CPU grounds.
  • Your solenoids (injectors, idle, etc) need ground return paths of a decent quality to function correctly, so I suspect 2A/2B are these. If I'm right, run these to two of the holes in your block of four injector grounds, and run a bridge from that same block to the LSD ground pin so they all share those two wires.
  • Your sensors, all of them, require a good clean ground reference at/through the ECU to avoid voltage drops in any line causing bad readings.


So 2D is right, I think. The others, see above :-)
m2cupcar wrote:RPM Hall/Opto
- configure: connect RPM0- and RPM1- to RPM0 RPM1 Shields
- R16, 17, 18, 19 = 1K 1/4w resistors
- R22, 83, 21, 84 = 1k 1/4w resistors
- R20, 23 = no resistors
- RPM0+ (crank) - 2E White CAS
- RPM- (cam) - 2G Yellow/Blue CAS
Should RPM- be RPM1+ ?
m2cupcar wrote:IGNITION (wasted)
- IG1 - 1G brown/yellow (cyl 1/4)
- IG2 - 1H brown (cal 3/4)
- JP1 - 5v
99.9% sure the ignition should be jumpered to 12V for these. They're darlington ignitors like most older stuff, right? Not LS1 coils or some such? If they are darlington, and you use 5V, it may run (like my ute), but it'll NEVER be right and never give a good strong spark.
m2cupcar wrote:Still trying to figure out the injector setup on the A7 and connections to the Miata harness/injectors.

FUEL INJECTORS
- Install 0ohm jumpers at JP3 JP4 & JP5
- INJ1 - 2Y green/white
- INJ2 - 2Z green
- INJ3 - 2U yellow
- INJ4 - 2V yellow/blue
(This is based on how the A3 injector connections were at P26, 27, 28, 29

What do I do for INJ1-GND, INJ2-GND, INJ3-GND, INJ4-GND?
And Injectors-IN?
See above, but probably 2A/2B for two of the INJ-GND pins, and a link to the LSD ground from a third hole.

The inputs need to be jumpered to CPU pins. There are four PORT T pins near the CPU, not far from the inputs, run four small reliable wires from those to these.

Hope that all helps!
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Re: Building the Brains for a Budget Racer: Jaguar A7 #42

Post by m2cupcar »

1) BRV (Battery Reference Voltage) will be ever so slight of a battery drain over time - not a huge deal, but something to consider
This is the fused side of where the positive cable from the battery arrives in the engine bay in the main fuse box.
3) There is another third 12V input for the ignition drivers, HSD, and LEDs that you need to hook up and haven't listed.
I found it- IGN-12v @ LSD 3 & 4.
5) O2 and EGR grounds have heater/solenoid current dumped through them?
No- all the power grounds are separate. This ground reference for the sensors. EGR is a position sensor, not solenoid.
  • Your PCB needs a solid reference ground, quite possibly the combination of 2C 1K 2F could provide this? Not sure. 2A/2B look highly attractive, but I don't see high current return paths available for the injectors and other junk if you use those for your CPU grounds.
There are plenty of “free” pins/leads to use as solitary grounds for the injectors and other junk.
  • Your solenoids (injectors, idle, etc) need ground return paths of a decent quality to function correctly, so I suspect 2A/2B are these. If I'm right, run these to two of the holes in your block of four injector grounds, and run a bridge from that same block to the LSD ground pin so they all share those two wires.
Got it.
  • Your sensors, all of them, require a good clean ground reference at/through the ECU to avoid voltage drops in any line causing bad readings.

So 2D is right, I think.
Agreed.
Should RPM- be RPM1+ ?
Yes!
99.9% sure the ignition should be jumpered to 12V for these. They're darlington ignitors like most older stuff, right? Not LS1 coils or some such? If they are darlington, and you use 5V, it may run (like my ute), but it'll NEVER be right and never give a good strong spark.
Every reference I found was 5v- the coils changed in 94, and the ignitor is now part of the coil internally. I’ll do some research to verify.
...probably 2A/2B for two of the INJ-GND pins, and a link to the LSD ground from a third hole.
The inputs need to be jumpered to CPU pins. There are four PORT T pins near the CPU, not far from the inputs, run four small reliable wires from those to these.
Hope that all helps!
Tremendously- much appreciated. :)
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Re: Building the Brains for a Budget Racer: Jaguar A7 #42

Post by Fred »

There may be free pins, but you should be able to use the existing wiring almost entirely, especially for something so fundamental. If that threesome of ground wires is decent, that could be the low current CPU reference. Then the two block direct ones are yours for the taking.

Another option is one block ground for CPU and the other for solenoids, but I doubt this is right.

Finally, you could do it M$ style, use the two block grounds, and share them with everything internally. I'd avoid this, though...

Re internal ignitors, that does not mean that they are logic level, only that they are built in. Later R33 skylines did the same trick IIRC. Signal from ECU stayed the same (12V! Proven!) but the ignitors went into the coils. If the only references you can find are M$ references, it's important to note that they still have this wrong even in their MS3Pro boxes which are essentially equivalent to the mess I made on my old Puma board trying to beef it up. I was misguided and that was around the time when I was researching how it was supposed to work and finding out all M$ advice had been utterly wrong for years and years. Sorry for the interlude, but it seemed relevant.

Keep in mind that these ignition outputs are buffered with resistors, so although you get 12V, you do not get full current supplied, only a max of about 150mA IIRC, less to anything that's not at zero volts.

I'll tweak your RPM section now. DONE.

EDIT: The ground I was referring to for the 4 LSD drives is called "OUTPUT-GND" I think, visible in your photo above.
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Re: Building the Brains for a Budget Racer: Jaguar A7 #42

Post by Fred »

Wait! I have a set of these 94 up coils! They're on my KP60 and I do believe we ran them with 12V successfully! :-D Confused the f*** out of us for a while, as I had assumed they were "just coils", but I was wrong. viewtopic.php?f=3&t=2654

99.99% sure my whore jaguar is setup for 12V hard wired. It has switchable VR/hall, switchable HSD/LSD, but that's about it IIRC.
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Re: Jaguar A7 cpu-to-injector-IN

Post by m2cupcar »

The inputs need to be jumpered to CPU pins. There are four PORT T pins near the CPU, not far from the inputs, run four small reliable wires from those to these.
Like this?
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Re: Building the Brains for a Budget Racer: Jaguar A7 #42

Post by Fred »

Yes, and do it in such a way that it doesn't cover the port B (useful), or BDM (just in case) pins. Also, did you ask me via email about the fan? PK4/LSD2, right there in the photo :-) If you jumper that first with a piece of copper resistor lead then you can run your wires over the top. I did it with nice little Teflon/PTFE wires on mine a while back, but it was a pain as that stuff is really hard to strip and really springy to route. End result was nice, though. I can't find any pics of that jumpering, and my 0.7 is with a friend right now (should see it tonight, though), however there are these three pics that sort of show the wire, how thin it is, how springy it is, but not that it's tinned multistranded flex and not that it's teflon :-)

Image

Image

Image
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